Such a device is known from German published specification No. 35 01 288 (U.S. Pat. No. 4,691,559, English patent specification No. 58 03 109 and Japanese Patent Application No. 87647/85).
It shows a test body 67 and a bar device around and in the transverse plane 21. The measuring device 74 measures on the basis of probes for measuring the thickness of thin layers. The rotor of an energizer 31 is pivotable about a pivot center while a stator is rigidly connected to the plate 16 belonging to the housing. A first geometric longitudinal axis lies in the transverse plane 21. This is the vertical axis 54.
A similar device is also described in German published specification No. 34 08 554 (U.S. Pat. No. 4,671,104, English Pat. No. 21 55 639 and Japanese published specification No. 75655/84).
Where these devices are concerned, the bar device or at least a part of the bar device is connected to the housing via a pivot bearing. So that they can rotate, such pivot bearings must in any case have some clearance, whatever form it may take. This limits the accuracy of the measuring device. Furthermore, the bar device is connected to the energizer by a further very long bar device (or by an arm 37 in the case of DE-OS 35 01 288). This has various disadvantages. For example, the housing is longer by this length. The current noise in the winding 136 is amplified by the lever ratio. The term current noise is meant to imply that the coil current cannot always be kept constant, for various reasons.
The result of measurement is also adversely affected in that the arm 37 is subject to bending. If it is desired to prevent this bending, then it must be made very thick in the bending direction, which entails mass, so that the measuring system becomes more sluggish and the instrument becomes heavier and also any transit locking devices have to be more rugged.
Furthermore, it is to a certain extent a problem to generate a linear force.
Devices, therefore, according to the relevant prior art include
a housing,
a bar device having an end portion and pivotable about a pivot center,
a test body and a probe supported on the end portion,
a measuring device which works on the basis of probes for measuring the thickness of thin layers,
an energizing means acting on the bar device having a first part rigid with the housing and a second part rigid with the bar device, and
a geometric first longitudinal axis passing through the center of the probe and the center of the test body.